Video compression is used in a variety of current and emerging products. Video compression is used in digital television set-top boxes, digital satellite systems, high definition television (HDTV) decoders, digital versatile disk (DVD) players, video conferencing, and other digital video applications. Video compression allows images of video content to be compressed by removing non-essential features of the video content. Compressing video content reduces the storage area needed to store the content. Compressed video content may be transmitted faster than un-compressed video content.
There are a variety of video coding methods that compress digital video content. Video coding standards have been developed to standardize the various video coding methods so that the compressed digital video content is rendered in formats that video encoders and decoders can recognize. For example, the International Telecommunication Union (ITU) in cooperation with the International Standards Organization (ISO) has developed the MPEG-4 Advanced Video Coding (AVC)/H.264 standard. There are multiple manipulations of video content when compressing the video content with the H.264 standard. For example, the H.264 standard will operate on portions of an image known as macroblocks (H.264 MBs). Each H.264 MB may be a 16×16 array of pixels. In intra frame encoding, the H.264 MBs are encoded using either an intra4 mode of encoding or an intra16 mode of encoding.
Cost values are determined for the intra4 and the intra16 modes of encoding to determine which intra mode will be used. The cost values indicate how well a specific H.264 MB will be represented by one of the intra4 or intra16 modes. Nine cost values need to be determined for nine intra4 modes. The nine intra4 modes are comprised of eight cost values associated with encoding an H.264 MB in one of eight directions. The ninth intra4 mode uses an average of pixel values to approximate the other pixel values and is not associated with a direction. Four cost values are determined for four intra16 modes. The intra mode with the smallest cost value is selected for encoding the H.264 MB after these thirteen cost values are determined. Calculating nine intra4 and four intra16 cost values is computationally expensive. A more effective way of encoding image data may be desired.